Micro-scale Modelling of the Urban Wind Speed for Air Pollution Applications

Modelling wind speeds in urban areas have many applications e.g. in relation to assessment of wind energy, modelling air pollution, and building design and engineering. Models for extrapolating the urban wind speed exist, but little attention has been paid to the influence of the upwind terrain and the foundations for the extrapolation schemes. To analyse the influence of the upwind terrain and the foundations for the extrapolation of the urban wind speed, measurements from six urban and non-urban stations were explored, and a model for the urban wind speed with and without upwind influence was developed and validated. The agreement between the wind directions at the stations is found to be good, and the influence of atmospheric stability, horizontal temperature gradients, land-sea breeze, temperature, global radiation and Monin-Obukhov Length is found to be small, although future work should explore if this is valid for other urban areas. Moreover, the model is found to perform reasonably well, but the upwind influence is overestimated. Areas of model improvement are thus identified. The upwind terrain thus influences the modelling of the urban wind speed to a large extent, and the fundamental assumptions for the extrapolation scheme are fulfilled for this specific case

Integrated photoelectrochemical (PEC)-forward osmosis (FO) system for hydrogen production and fertigation application

This study proposes an integrated system that combines a photoelectrochemical (PEC) system and forward osmosis (FO) system in tandem operation to address water, energy, and food (WEF) scarcity. The system utilizes a combination of ammonium sulfite and ammonium sulfate solution to represent wet flue gas desulfurization products from the ammonia scrubbing process commonly used in oil and gas producing countries. Under simulated sunlight, the sulfurous solution in the PEC system is oxidized at a reduced titania nanotube array (TNA) working electrode to produce hydrogen, a clean energy source (Energy). The oxidized sulfurous solution entering the draw solution (DS) compartment of the FO unit was then diluted when the FO system operates against simulated brackish water as the feed solution (FS, Water). The DS effluent is recirculated to ensure continuous operation of both PEC and FO systems. At a certain point in time, the DS effluent is also used as a cultivation solution for basil plants, the growth is visually more favorable compared to those supplied with tap water (Food). A concentrated DS (0.8:0.2 ratio of (NH4)2SO3:(NH4)2SO4) showed excellent water desalination performance. It had a high water flux of 17 LMH with 11.8 % water recovery, highest salt rejection (98.6 % for Na+ and 98.3 for Cl−), and lowest reverse solute flux (RSF) (3.5 g‧m−2‧h−1 for SO42−, 5.25 g‧m−2‧h−1 for SO32−, 3.1 g‧m−2‧h−1 for NH4+) against 5 g‧L−1 NaCl FS for 5 h, with a cathodic current density of 0.15 A‧cm−2. Overall, this study demonstrates the successful implementation of a bench-scale integrated system that produces tangible outcomes for water, energy, and food.This study was made possible by financial support from the Qatar National Research Fund (QNRF) under National Priorities Research Grant (NPRP) grant (NPRP 9-052-2-020). Open Access funding was provided by the Qatar National Library (QNL). H.P. is grateful to the National Research Foundation of Korea (2018R1A6A1A03024962, 2019R1A2C2002602, and 2021K1A4A7A02102598).Scopu